在spring4+hibernate4整合过程中，使用@Transactional注解事务会报"Exception in thread "main" org.hibernate.HibernateException: save is not valid without active transaction"错误，具体错误如下：
Exception in thread "main" org.hibernate.HibernateException: save is not valid without active transaction
at org.hibernate.context.internal.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:352)
at $Proxy18.save(Unknown Source)
at com.zainagou.dao.UserDaoImpl.addUser(UserDaoImpl.java:23)
at com.zainagou.dao.UserDaoImpl$$FastClassBySpringCGLIB$$98e1b102.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653)
at com.zainagou.dao.UserDaoImpl$$EnhancerBySpringCGLIB$$ac7c23a8.addUser(<generated>)
at com.zainagou.dao.MyTest.main(MyTest.java:19)
，后来发现是由于使用了如下配置导致上述问题：
<!-- session绑定当前线程 -->
<prop key="hibernate.current_session_context_class">thread</prop>
改配置在单独使用hibernate时进行当前线程绑定，在spring+hiberante整合中不需要这句配置，
spring提供了一个SpringSessionContext这个类来帮你获得和管理session